The goal of this Research Career Award is to elaborate on the mechanisms that link genetic characteristics and the social environment to 2 important outcomes among adolescents and young adults: (1) ill-health and (2) delinquency. This project will pay particular attention to the social context in which known genetic risk factors are given expression as well as genetic characteristics that facilitate resiliency in the face of social disadvantage. The project will build on the existing infrastructural capacity, cross-disciplinary collaboration, and mentorship available at the University of Colorado at Boulder in the emerging discipline of behavioral genetics. This training proposal includes: (1) direct instruction and supervision by leading experts in the substantive and methodological area of behavioral genetics, (2) enrollment in courses and seminars by researchers in social science, behavioral science, and medical science disciplines, (3) participation in workshops in sibling association and linkage analysis methodologies, and (4) regular participation in national conferences in population studies and behavioral genetics. The research proposal aims to utilize data from the National Longitudinal Study of Adolescent Health and the Rochester Youth Developmental Survey in conjunction with genetic information of respondents to examine the interaction between biological characteristics of individuals and their immediate social environment as determinants of differential developmental trajectories in the early stages of the life course. The long-term goal of this project is to collect original data in an effort to highlight the social determinants of genetic expression. These studies would be structured around the hypotheses and findings that stem from this project.